Typically, maintenance of computers included in a load balancing scheme includes the removal of those computers from the load balancing scheme. Removal of the computers from the load balancing scheme or environment often includes forcing or requesting that all pending processing requests in a computer cease. In some instances, load balanced computers may receive a processing request from a load balancer server at any given time. Thus, removing a computer may require that the load balancer server stop issuing processing requests. The time it can take to terminate the processes running on a computer can be significant.
In some instances, maintaining load balanced computers can be accomplished using a maintenance window that causes the load balanced service to be unavailable at particular points in time, and sometimes force or cause the termination of any pending requests. Typically these maintenance windows are artificially created by an administrator and involve forcing the termination of all services so that maintenance can be performed on all computers in the group at the same time. Using a maintenance window to maintain load balanced computer may not be suitable for all workloads. Further, there are drawbacks to using maintenance windows such as the inability to terminate a request. Furthermore, service unavailability may be undesirable, i.e. for an environment that needs a system that is operative twenty-four hours a day, seven days a week. In some embodiments, utilization patterns of a service may be unpredictable, resulting in difficulty in scheduling a maintenance window. A compromise, such as providing a short maintenance window, may be inadequate for handling a large group of computers. Still other drawbacks may include difficulty or inability in handling certain exceptions, and/or a requirement that a maintenance window starts and ends during non-working hours.
Still another method can include manually removing computers from a group of load balanced computers. Drawbacks to this method include the risk involved with an unanticipated need for a longer period of time to perform maintenance. There exists a need for a method of maintaining load balanced computers that avoids the drawbacks of present methods.